Abstract

Introduction

Resting energy expenditure (REE) increases after an intense exercise; however, little is known concerning mechanisms.

Purpose

The purpose of this study was to determine effects of a single bout of moderate-intensity continuous (MIC) aerobic exercise, or high-intensity interval (HII) exercise on REE under energy balance conditions.

Methods

Thirty-three untrained premenopausal women were evaluated at baseline, after 8–16 wk of training, 22 h after either MIC (50% peak V˙O2) or HII (84% peak V˙O2). Participants were in a room calorimeter during and after the exercise challenge. Food intake was adjusted to obtain energy balance across 23 h. REE was measured after 22 h after all conditions. Twenty-three-hour urine norepinephrine concentration and serum creatine kinase activity (CrKact) were obtained. Muscle biopsies were obtained in a subset of 15 participants to examine muscle mitochondrial state 2, 3, and 4 fat oxidation.

Under energy balance conditions, REE increased 22 h after both moderate-intensity and high-intensity exercise. Exercise-induced muscle damage/repair and increased sympathetic tone may contribute to increased REE, whereas uncoupled phosphorylation does not. These results suggest that moderate- to high-intensity exercise may be valuable for increasing energy expenditure for at least 22 h after the exercise.